Hi ofito! Welcome to Ukraine forum :)
There’s nothing scary in travelling around Ukraine – I’ve been to many dodgier places ;) However, do stay street smart while getting around here and do take the usual safety cautions in an unknown environment.
I’m not quite sure I got your plans all right from the way you wrote it – are you actually staying in Izmail or in Odessa? Your question #1 implies it’s Odessa but then I don’t see why you are doubting you can have enough time for the city then?
In any case, within a week you have budgeted for this trip you surely can include Izmail, Vilkovo and Odessa no problem. Vilkovo is normally done on a day trip, even if you add a boat sail around the Danube natural reserve area to it. Odessa does require at least couple of days to get a feel to it.
Izmail is in some 230-240km from Odessa (one-way, by automobile road). So in principle it’s not a problem to get there on a day trip from Odessa, although it’s going to be a long day. It takes about 4hrs by bus (and there are some leaving Odessa very early in the morning) and about 2-2.5hrs by car.
And Vilkovo is about half-way from Izmail to Odessa. So if I were to plan this trip, to avoid extra time on road, I’d stay in Izmail overnight (do not expect much comfort there, but for one night only even a camp or recreation base can be a good idea), visited Vilkovo from there then proceeded to Odessa.
When I’ve been to Vilkovo several years ago, we just drove to the area then found some locals on spot to get us around in their boats (obviously not an option to you). Some colleagues of mine used a local company in Vilkovo for a pre-arranged tour. I can PM you the details of that company, if you wish. I’m not sure though if they have any English speaking guides; you’ll have to ask them.
There are lost of tour companies in Odessa not only offering tours around the city to foreigners, but also arranging day trips to Vilkovo, which is a very popular side trip from Odessa. Search the web, I’m sure you‘ll find many.
Also, try to contact those TA members who’ve been to Odessa and ask if they used a tour company or a guide. Send a PM to those who left their trip reports here tripadvisor.com/…28348864 (look for Odessa reports).
A convinced solo (and independent) traveller myself, I do encourage you to learn basic Cyrillics (Russian will do for this leg of your trip) before heading here; it’ll help you to get around a lot!
As Anna said, do not count much on information kiosks here to get a conversation guide – better be ready in advance. In addition to the link Anna posted above, you might probably also find the following helpful:
Some place names you can come across in the city in #6 here tripadvisor.com/ShowTopic-g295368-i5302-k417…
Names of some local food and bevarages in #3 and 5 here tripadvisor.com/ShowTopic-g294474-i3663-k318…
Digits and numbers tripadvisor.com/Travel-g294473-c153417/Ukrai…
LP phrasebooks can also get handy, easy to purchase on-line …lonelyplanet.com/russia/russian-phrasebook-5 and …lonelyplanet.com/ukraine/ukrainian-phrasebo…
Enjoy your trip planning! :)